SUMMARY Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants…
RsrA, an anti‐sigma factor regulated by redox change
A redox‐sensitive, σR‐specific anti‐sigma factor, RsrA, is identified, which binds ρR and inhibits σG‐directed transcription in vitro only under reducing conditions and correlated with intramolecular disulfide bond formation in £rA.
Mechanism and cleavage specificity of the H-N-H endonuclease colicin E9.
The data show that the H-N-H motif is an adaptable catalytic centre able to hydrolyse nucleic acid by different mechanisms depending on the substrate and metal ion regime.
Mutational analysis of RsrA, a zinc‐binding anti‐sigma factor with a thiol–disulphide redox switch
It is proposed that a thiol–disulphide redox switch is formed between two of C11, C41 and C44, and that all three residues play an essential role in anti‐sigma factor activity in their reduced state, perhaps by acting as ligands for zinc.
Cell entry mechanism of enzymatic bacterial colicins: porin recruitment and the thermodynamics of receptor binding.
- N. G. Housden, S. Loftus, G. Moore, R. James, C. Kleanthous
- BiologyProceedings of the National Academy of Sciences…
- 27 September 2005
It is demonstrated that although colicin unfolding is undoubtedly a prerequisite for E. coli cell death, it must occur after assembly of the translocon, and the immunity protein is not released during its assembly.
The Role of zinc in the disulphide stress-regulated anti-sigma factor RsrA from Streptomyces coelicolor.
Swimming against the tide: progress and challenges in our understanding of colicin translocation
- C. Kleanthous
- BiologyNature Reviews Microbiology
- 1 December 2010
These studies have highlighted some surprising similarities in the modes of action of the systems that colicins subvert, including the binding of outer-membrane nutrient transporters and porins and the subsequent recruitment of periplasmic and inner- Membrane proteins that, together, trigger translocation.
A structural comparison of the colicin immunity proteins Im7 and Im9 gives new insights into the molecular determinants of immunity-protein specificity.
This work is believed to be the first successfully refined crystal structure solved by molecular replacement using an NMR trial model with less than 100% sequence identity and provides a structural framework with which to understand immunity-protein specificity.
Homing in on the Role of Transition Metals in the HNH Motif of Colicin Endonucleases*
- A. Pommer, U. C. Kühlmann, C. Kleanthous
- Biology, ChemistryJournal of Biological Chemistry
- 17 September 1999
The data demonstrate that the transition metal is not essential for colicin DNase activity but rather serves a structural role, and it is speculated that the HNH motif has been adapted for use by endonuclease colicins because of its involvement in DNA recognition and because removal of the bound metal ion destabilizes the DNase domain.
Allosteric β‐propeller signalling in TolB and its manipulation by translocating colicins
Comparison of the TolB mechanism to that of vertebrate guanine nucleotide exchange factor RCC1 suggests that allosteric signalling may be more prevalent in β‐propeller proteins than currently realized.